As critical dimension (CD) of integrated circuit (IC) devices shrinks to 22 nm and below, extreme ultraviolet (EUV) lithography is becoming a leading technology for IC manufacturing. However, EUV lithography poses new challenges on electronic design automation (EDA) mask synthesis tools. Flare, or stray light due to mirror surface roughness on the mask, is one main concern for modeling and automatic mask synthesis. For example, the CD variation due to the flare can be over 10% of an intended CD. Thus, EDA mask synthesis tools should accurately model and correct for such flare effects.